Method and apparatus for geo-locating mobile station

ABSTRACT

A method for estimating a geographic location of a mobile station within a coverage area of a wireless network includes: determining a radial distance of the mobile station from a serving base station based on a round trip measurement and calculating an angular position of the mobile station in relation to the radial distance based on a first signal strength measurement, a second signal strength measurement, and an angular position reference that extends outward from the serving base station. The signal strength measurements representative of power characteristics of RF signals received by the mobile station from first and second sector antennas of the serving base station. An apparatus associated therewith includes a distance module to perform the determining and an angular position module to perform the calculating. The apparatus may be implemented in a base station, a geo-location service node, a network management node, or other communication nodes.

BACKGROUND

This disclosure relates to providing wireless service to a mobilestation in a wireless network and more particularly, but notexclusively, to estimating a geographic location for a mobile stationwithin a coverage area of a wireless network.

Geographic location information for mobile stations has tremendous valueto mobile applications, network optimization (e.g., self optimizednetwork (SON)), capacity management, and drive test substitutions, etc.Although many modern mobile stations can obtain their own locations fromintegrated GPS modules, it is still a challenge for the network to trackthe locations of a large number of subscribers for an extended period oftime. A frequent location update from mobile stations would increasenetwork overhead and may overwhelm the network and create bottlenecks. Apassive location estimation technique that leverages measurements fromnormal network operation is desirable because it avoids such increasesin network overhead.

For example, in third generation (3G) code division multiple access(CDMA) networks, such as 3G1X, EVDO, UMTS, etc., one can triangulate thegeographic location of a mobile station from the reported round tripdelays between the mobile station and three or more base stations (seeFIG. 1). The corresponding round trip delays are sent back by the mobilestations for call processing, thus no additional signaling overhead isincurred by the network to collect measurements for triangulation.

However, this triangulation approach does not work in all networks, suchas the fourth generation (4G) long term evolution (LTE) networks. Unlike3G CDMA networks, each measurement report in LTE networks only containsthe round trip delay from one cell (i.e., the serving cell of themobile). Thus, the triangulation technique cannot be used at all inconjunction with 4G LTE networks.

For these and other reasons, there is a need to provide a technique forestimating a geographic location of a mobile station for at least 4G LTEnetworks. Additionally, it is desirable that the technique be compatiblewith other types of wireless networks, especially 3G CDMA networks. Itis also desirable that the technique be more reliable than thetriangulation technique.

SUMMARY

In one aspect, a method for estimating a geographic location of a mobilestation within a coverage area of a wireless network is provided. In oneembodiment, the method includes: determining a radial distance of amobile station from a base station serving the mobile station, the basestation including multiple sector antennas, the radial distance based atleast in part on a round trip measurement associated with elapsed timebetween sending an outgoing signal from the base station to the mobilestation and receiving a corresponding acknowledgement signal from themobile station at the base station; and calculating a current angularposition of the mobile station in relation to the radial distance fromthe serving base station based at least in part on a first signalstrength measurement, a second signal strength measurement, and anangular position reference that extends outward from the serving basestation, the first and second signal strength measurementsrepresentative of power characteristics of respective radio frequency(RF) signals received by the mobile station from corresponding first andsecond sector antennas of the serving base station.

In another aspect, an apparatus for estimating a geographic location ofa mobile station within a coverage area of a wireless network isprovided. In one embodiment, the apparatus includes: a distance modulefor determining a radial distance of a mobile station from a basestation serving the mobile station, the base station including multiplesector antennas, the radial distance based at least in part on a roundtrip measurement associated with elapsed time between sending anoutgoing signal from the base station to the mobile station andreceiving a corresponding acknowledgement signal from the mobile stationat the base station; and an angular position module in operativecommunication with the distance module for calculating a current angularposition of the mobile station in relation to the radial distance fromthe serving base station based at least in part on a first signalstrength measurement, a second signal strength measurement, and anangular position reference that extends outward from the serving basestation, the first and second signal strength measurementsrepresentative of power characteristics of respective RF signalsreceived by the mobile station from corresponding first and secondsector antennas of the serving base station.

In yet another aspect, a non-transitory computer-readable medium storingprogram instructions is provided. The program instructions, whenexecuted by a computer, cause a corresponding computer-controlled deviceto perform a method for estimating a geographic location of a mobilestation within a coverage area of a wireless network. In one embodimentof the non-transitory computer-readable medium, the method includes:determining a radial distance of a mobile station from a base stationserving the mobile station, the base station including multiple sectorantennas, the radial distance based at least in part on a round tripmeasurement associated with elapsed time between sending an outgoingsignal from the base station to the mobile station and receiving acorresponding acknowledgement signal from the mobile station at the basestation; calculating a current angular position of the mobile station inrelation to the radial distance from the serving base station based atleast in part on a first signal strength measurement, a second signalstrength measurement, and an angular position reference that extendsoutward from the serving base station, the first and second signalstrength measurements representative of power characteristics ofrespective RF signals received by the mobile station from correspondingfirst and second sector antennas of the serving base station; andidentifying a current geographic location of the mobile station in acoverage area of the wireless network in a geographic notation based atleast in part on combining the radial distance and current angularposition of the mobile station relative to the serving base station.

Further scope of the applicability of this the present invention willbecome apparent from the detailed description provided below. It shouldbe understood, however, that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art.

DESCRIPTION OF THE DRAWINGS

The present invention exists in the construction, arrangement, andcombination of the various parts of the device, and steps of the method,whereby the objects contemplated are attained as hereinafter more fullyset forth, specifically pointed out in the claims, and illustrated inthe accompanying drawings in which:

FIG. 1 is a functional diagram showing three cells of a wireless networkin relation to an exemplary embodiment of a triangulation technique forestimating the geographic location of a mobile station;

FIG. 2 is a functional diagram showing a serving cell of a wirelessnetwork in relation to an exemplary embodiment of another technique forestimating the geographic location of a mobile station;

FIG. 3 is a graph showing a transmit antenna gain characteristic for asector antenna of a base station in which normalized gain in dB isplotted in relation to look angles from the sector antenna to a mobilestation in relation to azimuth (i.e., horizontal gain) and elevation(i.e., vertical gain) positions from the orientation of the sectorantenna;

FIG. 4 is a flow chart of an exemplary embodiment of a process forestimating a geographic location of a mobile station within a coveragearea of a wireless network;

FIG. 5, in combination with FIG. 4, is a flow chart of another exemplaryembodiment of a process for estimating a geographic location of a mobilestation within a coverage area of a wireless network;

FIG. 6 is a block diagram of an exemplary embodiment of an apparatuswithin a serving base station of a wireless network for estimating ageographic location of a mobile station within a coverage area of thewireless network;

FIG. 7 is a block diagram of an exemplary embodiment of an apparatuswithin a geo-location service node of a wireless network for estimatinga geographic location of a mobile station within a coverage area of thewireless network;

FIG. 8 is a block diagram of an exemplary embodiment of an apparatuswithin a network management node associated with a wireless network forestimating a geographic location of a mobile station within a coveragearea of the wireless network;

FIG. 9 is a block diagram of an exemplary embodiment of an angularposition module associated with the apparatus shown in FIGS. 6-8;

FIG. 10 is a flow chart of an exemplary embodiment of a process forestimating a geographic location of a mobile station within a coveragearea of a wireless network performed by a computer-controlled deviceexecuting program instructions stored on a non-transitorycomputer-readable medium;

FIG. 11 is a bird's eye view of a coverage area of an exemplary basestation in a wireless network showing an estimated geographic locationand a GPS location for a mobile station; and

FIG. 12 is a set of graphs showing azimuth gain parametercharacteristics for two sector antennas of a base station, elevationgain parameter characteristics for the two sector antennas, a compositegraph showing the difference between gains for the two sector antennas,and a graph of a function of the angular position of the mobile stationin relation to the delta antenna gain component, a delta transmitparameter component, and a delta signal strength measurement component.

DETAILED DESCRIPTION

Various embodiments of methods and apparatus provide techniques forestimating a geographic location of a mobile station within a coveragearea of a wireless network. In one embodiment, an algorithm estimates ageographic location of mobile station that reports signal strengthmeasurements from multiple sector antennas of a serving base station ina wireless network in which the serving base station reports a roundtrip measurement associated with the mobile station. For example, thevarious embodiments of the geographic location estimating algorithm canbe use to estimate the location of a mobile station in a 4G LTE network.Various embodiments of the algorithm can also estimate the location of amobile station in 3G CDMA wireless networks and other types of wirelessnetworks that use base stations with multiple sector antennas.

With reference to FIG. 2, in one embodiment, the technique forestimating the geographic location of the mobile station uses a roundtrip measurement (e.g., RTD measurement) from a serving base station(i.e., serving cell) to estimate the distance (d) of the mobile stationfrom the serving base station. Then, signal strength measurements fromserving and/or neighboring sectors of the serving base station toestimate an azimuth position (φ) of the mobile station in relation to anangular position reference extending outward from the serving basestation. Combining the sector coverage areas of the same base stationforms a corresponding cellular coverage area for the base station. Theindividual sector coverage areas may also be referred to as cells inrelation to corresponding sector antennas. If so, the correspondingcells for sector antennas associated with the same base station arestill usually labeled as sectors (e.g., α, β, γ sectors or sectors 1, 2,3). Normally, the sector antennas associated with the same base stationare mounted on the same cell tower (or building). Hence, the radio wavetravel from these sector antennas to a given mobile station antenna willexperience highly correlated losses (including path loss and shadowfading). The algorithm described herein uses these RF characteristics(i.e., highly correlated losses) to estimate an azimuth position of themobile station in relation to the serving based station based on thedifference of signal strength measurements from multiple sector antennasof the serving base station.

In one embodiment, the algorithm for estimating a geographic location ofa mobile station within a coverage area of a wireless network beginswith estimating a distance (d) of the mobile station from the servingbase station based on a round trip measurement, such as RTD. Next, theazimuth position (φ) of the mobile station in relation to the servingbase station is estimated based on signal strength measurements by themobile station from multiple sector antennas of the serving base stationthat are reported back by the mobile station to the serving base stationvia the serving sector antenna. Combining the distance (d) and azimuthposition (φ) forms a geographic location of the mobile station inrelation to the serving base station with respect to vector representedby a displacement (i.e., distance (d)) and an angular position (i.e.,azimuth position (φ)). This polar coordinate-type of geographic notationcan be converted to various other forms of geographic notation,including a latitude/longitude notation, an address notation, or ageo-bin tile grid notation associated with the coverage area for thewireless network. For example, the geo-bin tile grid notation may use 50meter by 50 meter tiles to represent the coverage area for a sectorantenna, base station, cluster of base stations, or the overall wirelessnetwork. In other embodiments, any suitable tile size may be used toprovide a higher or lower resolution of the coverage area.

The approximation algorithm for estimating the geographic location of amobile station may be based on certain considerations regarding themobile received power (Pr) (i.e., signal strength measurements) frommultiple sector antennas where the sector antennas are located in closeproximity to each other, such as mounted on the same cell tower or onthe same physical structure at relatively the same elevation. Forexample, the mobile received power (Pr) is received by the mobilestation from multiple sector antennas of the serving base station. Themobile station measures the signal strength of the mobile received power(Pr) signals and may report back the corresponding signal strengthmeasurements in dBm.

Mobile received power (Pr) may be represented by the following equation:

Pr(d, φ, θ)=Pt−PL(d)−X+Gt(d, φ, θ)+Gr  (1),

where d is a distance between the serving base station and the mobilestation in kilometers (km), φ is an azimuth position of the mobilestation in relation to an angular position reference extending outwardfrom the serving base station, θ is an azimuth position at which thetransmit portion of the corresponding sector antenna is oriented inrelation to the angular reference position, Pt is a transmit power forthe corresponding sector antenna in dBm, and PL(d) is an average pathloss in dB for the corresponding sector antenna. The azimuth position θof the sector antenna is known and corresponds to its actualinstallation. Likewise, the transmit power Pt for the sector antenna isknown at the serving base station based on known characteristics of thesector antenna or actual measurements by the base station.

The average path loss PL(d) may be represented by the followingequation:

PL(d)=K1+K2*log 10(d)  (2),

where K1 and K2 are propagation parameters such that K1 is function ofmorphology, frequency, cell antenna height, and mobile antenna heightand K2 is function of cell antenna height.

With reference again to equation (1), X is a zero-mean Gaussiandistributed random variable (in dB) with standard deviation σapproximately equal to N(0, σ). (in dB). X may be referred to as theshadowing fading effect. Gt(d, φ, θ) is the transmit antenna gain at thesector antenna in dB. Gr is receive antenna gain at the mobile stationin dB.

With reference to FIG. 3, Gt(d, φ, θ) reflects that Gt is a function ofmobile distance (d) and an angle between the azimuth position (φ) of themobile station and the azimuth position (θ) of the corresponding sectorantenna. Note, the distance (d), in combination with the sector antennaheight, is used to estimate an antenna tile and an antenna downtile. Theazimuth position (φ) of the mobile station and the azimuth position (θ)of the corresponding sector antenna are used to determine a horizontalgain portion of Gt, where the look angle is φ−θ. The distance (d) andthe height (i.e., elevation) of the corresponding sector antenna areused to determine a vertical gain component of Gt.

The signal strength measurements for mobile received power Pr may bereported as received signal reference power (RSRP) measurements,reference signal received quality (RSRQ) measurements, or Ec/Iomeasurements. RSRQ is the ratio of received signal reference power tototal received power. Ec/Io is the ratio in dB between the pilot energyaccumulated over one PN chip period (“Ec”) to the total power spectraldensity in the received bandwidth (“Io”).

Mobile received power Pr1 and Pr2 from two sector antennas of theserving base station in dBm may be represented by the followingequations:

Pr1(d, φ, θ1)=Pt1−PL(d)−X+Gt1(d, φ, θ1)+Gr  (3),

Pr2(d, φ, θ2)=Pt2−PL(d)−X+Gt2(d, φ, θ2)+Gr+ε  (4).

The path loss and shadowing fading effect from different sector antennasof the same base station can be assumed to be equal where the sectorantennas are mounted on the same cell tower or building. The closeproximity of the sector antennas results in high correlation of betweenthese components of the mobile received power Pr1 and Pr2. For example,the differences of shadow fading are expected to be very small and arecounted by ε in equation (4). As mentioned above, d, θ1 and θ2 are knownvalues.

Based on the foregoing, an estimate of the azimuth position (φ) of themobile station may be based on the difference of mobile received powerfrom the two sector antennas (Pr1-Pr2) in dB. For example, (Pr1-Pr2) canbe (RSRP1-RSRP2) or (RSRQ1-RSRQ2) in an LTE network, Similarly,(Pr1-Pr2) can be (Ec/Io) 1-(Ec/Io) 2 in a CDMA network. Even though themobile received power Pr1 and Pr2 are expressed in absolute receivedpower format (i.e., dBm), the estimation of mobile location does notrequire the knowledge of absolute received power information. RSRQ forLTE and pilot Ec/Io for CDMA can be used in the same manner as mentionedabove.

Based on the foregoing, the difference between the mobile received powerPr1 and Pr2 can be represented by the following equation:

(Pr1−Pr2)=(Gt1(φ)−Gt2(φ))+(Pt1−Pt2)  (5),

where φ can be substituted with a potential azimuth position φm for themobile station in the range of 0 to 360 degrees. The potential azimuthposition φm that results in the closest match between the right and leftsides of equation (5) can be used as estimated azimuth position of themobile station.

Based on the foregoing, the azimuth position of the mobile station canbe represented by the following equation:

F(φ)=|(Gt1(φ)−Gt2(φ))+(Pt1−Pt2)−(Pr1−Pr2)|  (6),

where φ can be substituted with a potential azimuth position φm for themobile station in the range of 0 to 360 degrees. The potential azimuthposition φm that minimizes F(φm) can be used as estimated azimuthposition of the mobile station.

This process can also be expressed in the following equation:

min|(Gt1(φ)−Gt2(φ))+(Pt1−Pt2)−(Pr1−Pr2)|  (7).

Notably, the value selected for the initial potential azimuth positionθm in equations (5) through (7) can be based at least in part on theknowledge of the orientation and azimuth position of the serving sectorantenna. Subsequent values selected for the potential azimuth positionθm can be based on whether the subsequent result is approaching orreceding from the desired result. Various techniques can also be used toselect subsequent values for the potential azimuth position θm based onthe magnitude of the difference between the subsequent result and thedesired result as well as the change in the difference betweenconsecutive subsequent results and the desired result.

With reference to FIG. 11, a bird's eye view of a coverage area of anexemplary base station A in a wireless network shows an estimatedgeographic location for a mobile station (UE) resulting from the processdisclosed herein. A geographic location for the mobile station (UE)based on GPS location is also shown for comparison. The X and Y axes forthe coverage area reflect distance in meters from the base station A.Notably, the estimated geographic location is close to the GPS location.

The base station A includes a first sector antenna oriented at 27degrees from north (i.e., an angular position reference representing0/360 degrees) and a second sector antenna oriented at 267 degrees. Themobile station reported signal strength measurements from the first andsecond sector antennas at −11 dB and −13 dB, respectively. The angularposition of the mobile station was estimated at 330.6 degrees using theprocess disclosed herein. The measurements used to estimate thegeographic location of the mobile station were retrieved from per callmeasurement data (PCMD) for an active call associated with the mobilestation. For example, the PCMD data may be stored by a wireless serviceprovider during network operations for billing purposes. The processdisclosed herein may use signal strength measurements and round tripmeasurements captured and retained during network operations via anysuitable techniques without requiring additional network overhead forcollection of data to perform the estimate of the geographic location ofthe mobile station.

With reference to FIG. 12, various data and calculations associated withthe process for estimating the geographic location of a mobile stationis provided in a set of graphs. The upper left graph shows an azimuthgain parameter characteristic for a first sector antenna of a servingbase station. The first sector antenna is oriented at 27 degrees fromnorth (i.e., an angular position reference representing 0/360 degrees).The middle left graph shows an azimuth gain parameter characteristic fora second sector antenna of a serving base station. The second sectorantenna is oriented at 267 degrees from north. The azimuth gainparameter characteristics may be manufacturer's specifications of powermeasurements from the sector antennas from relatively close (e.g., 10meters) to the base station where little or no path loss is experienced.As shown, the first and second sector antennas have the same azimuthgain characteristic merely shifted by the orientation of the antennas.In other base station arrangements, the sector antennas may havedifferent azimuth gain characteristics.

The upper right graph shows an elevation gain parameter characteristicfor the first sector antenna. The first sector antenna is oriented at 2degrees down from horizontal (i.e., an elevation position referencerepresenting 0/360 degrees). The middle right graph shows an elevationgain parameter characteristic for the second sector antenna. The secondsector antenna is also oriented at 2 degrees down from horizontal. Theelevation gain parameter characteristics may be manufacturer'sspecifications of power measurements from the sector antennas fromrelatively close (e.g., 10 meters) to the base station where little orno path loss is experienced. As shown, the first and second sectorantennas have the same elevation gain characteristic. In other basestation arrangements, the sector antennas may have different elevationgain characteristics. Also, the sector antennas may be oriented atdifferent angles from the horizontal in other base station arrangements.

The lower left graph is a composite graph showing the difference betweengains for the first and second sector antennas. The composite graphtakes the azimuth and elevation gain characteristics into account toform a composite delta gain characteristic. The composite graph reflectsdifferences in relation to varying azimuth position that follows theazimuth gain characteristics and a relatively steady state componentfrom the elevation gain characteristics because the elevation tilt ofthe antennas is not changing. The following equation is used to populatethe composite graph:

(Gt1(φ)_(az) +Gt1_(el) −Gt1_(max))−(Gt2(φ)_(az) +Gt2_(el)+Gt2_(max))  (8),

where Gt1(φ)_(az) is the azimuth gain for the first sector antenna for agiven azimuth angle in relation to the angular position reference,Gt1_(el) is the elevation gain for the first antenna associated with theelevation tilt, and Gt1_(max) is the maximum gain for the first sectorantenna. Similarly, Gt2(φ)_(az) is the azimuth gain for the secondsector antenna for a given azimuth angle in relation to the angularposition reference, Gt2_(el) is the elevation gain for the secondantenna associated with the elevation tilt, and Gt2_(max) is the maximumgain for the second sector antenna.

The lower right graph shows a function of the angular position of themobile station in relation to the delta antenna gain component, a deltatransmit parameter component, and a delta signal strength measurementcomponent as defined above in equation (7).

With reference to FIG. 4, an exemplary embodiment of a process 400 forestimating a geographic location of a mobile station within a coveragearea of a wireless network begins at 402 where a radial distance of amobile station from a base station serving the mobile station isdetermined. The base station includes multiple sector antennas. Theradial distance is based at least in part on a round trip measurementassociated with elapsed time between sending an outgoing signal from thebase station to the mobile station and receiving a correspondingacknowledgement signal from the mobile station at the base station. At404, a current angular position of the mobile station in relation to theradial distance from the serving base station is calculated. The currentangular position is based at least in part on a first signal strengthmeasurement, a second signal strength measurement, and an angularposition reference that extends outward from the serving base station.The first and second signal strength measurements representative ofpower characteristics of respective RF signals received by the mobilestation from corresponding first and second sector antennas of theserving base station.

With reference to FIGS. 4 and 5, another exemplary embodiment of aprocess 500 for estimating a geographic location of a mobile stationwithin a coverage area of a wireless network includes the process 400 ofFIG. 4 and continues at 502 where a current geographic location of themobile station in a coverage area of the wireless network is identifiedin a geographic notation. The geographic notation is based at least inpart on combining the radial distance and current angular position ofthe mobile station relative to the serving base station. In oneembodiment, the radial distance and current angular position reflect apolar coordinate-type of geographic notation in reference to the servingbase station. In other embodiments, the radial distance and currentangular position can be converted into various types of geographicnotation, such as a latitude/longitude notation, an address notation, ora geo-bin tile grid notation associated with the coverage area for thewireless network.

In another embodiment, the process 500 also includes sending the currentgeographic location of the mobile station in the geographic notation toa geo-location storage node associated with the wireless network. In afurther embodiment, the determining, calculating, identifying, andsending are performed by the serving base station.

In yet another embodiment, the process 500 also includes receiving theround trip measurement, first signal strength measurement, and secondsignal strength measurement from the serving base station via thewireless network at a geo-location service node associated with thewireless network. In this embodiment, the current geographic location ofthe mobile station is sent in the geographic notation to a geo-locationstorage device associated with the geo-location service node. In theembodiment being described, the receiving, determining, calculating,identifying, and sending are performed by the geo-location service node.

In still another embodiment, the process 500 also includes receiving theround trip measurement, first signal strength measurement, and secondsignal strength measurement from the serving base station via thewireless network at a network management node associated with thewireless network. In this embodiment, the round trip measurement, firstsignal strength measurement, and second signal strength measurement arestored at a measurements storage device associated with the networkmanagement node. In the embodiment being described, the round tripmeasurement, first signal strength measurement, and second signalstrength measurement are retrieved from the measurements storage devicein conjunction with the determining and calculating. In this embodiment,the process 500 also includes sending the current geographic location ofthe mobile station in the geographic notation to a geo-location storagedevice associated with the network management node. The receiving,storing, retrieving, determining, calculating, identifying, and sendingare performed by the network management node in the embodiment beingdescribed.

With reference again to FIG. 4, in another embodiment of the process400, the round trip, first signal strength, and second signal strengthmeasurements are related in calendar time. In a further embodiment, theradial distance and current angular position of the mobile stationrelative to the serving base station are indicative of a currentgeographic location of the mobile station in a coverage area of thewireless network in relation to the calendar time associated with theround trip, first signal strength, and second signal strengthmeasurements.

In yet another embodiment of the process 400, the first sector antennais serving the mobile station and referred to as a serving sectorantenna and the second sector antenna is disposed near the first sectorantenna and referred to as a neighboring sector antenna. In stillanother embodiment of the process 400, the round trip measurement ismeasured by the serving base station. In a further embodiment, the roundtrip measurement includes a RTD time measurement. In still yet anotherembodiment of the process 400, the first and second signal strengthmeasurements are measured by the mobile station. In a furtherembodiment, the first and second signal strength measurements includeRSRP measurements, RSRQ measurements, or Ec/Io measurements.

In another embodiment of the process 400, the calculating in 404 mayinclude retrieving first and second transmit parameter values from astorage device associated with the wireless network. The first andsecond transmit parameter values representative of power characteristicsof respective communication signals to be transmitted by thecorresponding first and second sector antennas. In this embodiment, thecalculating in 404 may also include determining a difference between thefirst and second transmit parameter values to obtain a first angularposition component.

In a further embodiment of the process 400, the calculating in 404 mayalso include retrieving the first and second signal strengthmeasurements from the storage device. In this embodiment, thecalculating in 404 may also include determining a difference between thefirst and second signal strength measurements to obtain a second angularposition component.

In a yet further embodiment of the process 400, the calculating in 404may also include retrieving a first antenna elevation gain parametervalue, a first antenna maximum gain parameter value, and a first antennaazimuth gain parameter characteristic from the storage device. The firstantenna azimuth gain parameter characteristic relating first antennaazimuth gain parameter values to variable azimuth positions with respectto the angular position reference. The variable azimuth positionsrepresentative of prospective azimuth positions of the mobile station inrelation to the angular position reference. The first antenna azimuthgain parameter characteristic based at least in part on a first antennaposition value representative of a first azimuth position at which thefirst sector antenna is oriented in relation to the angular positionreference. In this embodiment, a second antenna elevation gain parametervalue, a second antenna maximum gain parameter value, and a secondantenna azimuth gain parameter characteristic are also retrieved fromthe storage device. The second antenna azimuth gain parametercharacteristic relating second antenna azimuth gain parameter values tothe variable azimuth positions. The second antenna azimuth gainparameter characteristic based at least in part on a second antennaposition value representative of a second azimuth position at which thesecond sector antenna is oriented in relation to the angular positionreference.

In the embodiment being described, an angular value (e.g., not exceeding360) may be selected for the variable azimuth position. The first andsecond antenna azimuth gain parameter characteristics may be used toidentify the corresponding first and second antenna azimuth gainparameter values for the variable azimuth position associated with theselected angular value. In this embodiment, the calculating in 404 maycontinue by determining a difference between first and second transmitantenna gains for the selected angular value. The difference may bedetermined by adding the first antenna azimuth gain parameter value forthe selected angular value to the first antenna elevation gain parametervalue and subtracting the first antenna maximum gain parameter value toobtain the first transmit antenna gain, adding the second antennaazimuth gain parameter value for the selected angular value to thesecond antenna elevation gain parameter value and subtracting the secondantenna maximum gain parameter value to obtain the second transmitantenna gain, and subtracting the second transmit antenna gain from thefirst transmit antenna gain to obtain a third angular positioncomponent.

The angular value selected for the initial variable azimuth position canbe based at least in part on knowledge of which sector antenna isserving the mobile station and the orientation and azimuth position ofthe serving sector antenna. Subsequent values selected for the variableazimuth position can be based on whether the subsequent result isapproaching or receding from the desired result. Various techniques canalso be used to select subsequent values for the variable azimuthposition based on the magnitude of the difference between the subsequentresult and the desired result as well as the change in the differencebetween consecutive subsequent results and the desired result.

For example, in a further embodiment of the process 400, the angularvalue initially selected for the variable azimuth position may bebetween the first and second antenna position values. In thisembodiment, the initial angular value may be representative of amid-point between the first and second antenna position values. In otherwords, if the first antenna is oriented to 120 degrees in relation tothe angular reference position, a second antenna may be oriented to 240degrees, and 180 may be selected as the initial angular value for thevariable azimuth position because it is at a midpoint between the firstand second sector antennas. The selection of other angular values forthe variable azimuth position can take into account whether the resultsare getting better or worse to select angular values to obtain betterresults. The iterative selection of angular values can be incremental orbased on a factor of the difference between the obtained result and thedesired result.

In still another further embodiment of the process 400, the calculatingin 404 also includes adding the first and third angular positioncomponents and subtracting the second angular position component to forman arithmetic result. In the embodiment being described, the arithmeticresult is converted to an absolute value. In this embodiment, if theabsolute value is within a predetermined threshold of a desired value(e.g., zero), the process 400 continues by identifying the angular valuesubstituted for the variable azimuth position as the current angularposition for the mobile station. Otherwise, the process 400 repeats theselecting with a different angular value, repeats the determining of thedifference between the first and second transmit gains to obtain a newvalue for the third angular position component, repeats the adding andsubtracting to form the arithmetic result and the determining of theabsolute value, and continues the repeating until the absolute value iswithin the predetermined threshold of the desired value.

In still yet another further embodiment of the process 400, thecalculating in 404 also includes adding the first and third angularposition components and subtracting the second angular positioncomponent to form an arithmetic result. In this embodiment, thearithmetic result is converted to an absolute value. In the embodimentbeing described, the process 400 repeats the selecting with a differentangular value, repeats the determining of the difference between thefirst and second transmit gains to obtain a new value for the thirdangular position component, repeats the adding and subtracting to formthe arithmetic result and the determining of the absolute value, andcontinues the repeating until the absolute value is minimized. In thisembodiment, the process 400 continues by identifying the correspondingangular value substituted for the variable azimuth position for whichthe absolute value is minimized as the current angular position for themobile station.

In another further embodiment of the process 400, the calculating in 404includes summing the first and third angular position components to forman arithmetic result and comparing the arithmetic result to the secondangular position component. In this embodiment, if the arithmetic resultis within a predetermined range of the second angular positioncomponent, the process 400 continues by identifying the angular valuesubstituted for the variable azimuth position as the current angularposition for the mobile station. Otherwise, the process 400 repeats theselecting with a different angular value, repeats the determining of thedifference between the first and second transmit gains to obtain a newvalue for the third angular position component, repeats the summing ofthe first and third angular position components to form the arithmeticresult and the comparing of the arithmetic result to the second angularposition component, and continues the repeating until the arithmeticresult is within the predetermined range of the second angular positioncomponent.

With reference to FIG. 6, an exemplary embodiment of an apparatus forestimating a geographic location of a mobile station 600 within acoverage area of a wireless network 602 includes a distance module 604and an angular position module 606. The distance module 604 determines aradial distance of the mobile station 600 from a base station 608serving the mobile station 600. The base station 608 includes multiplesector antennas (e.g., 610, 612, 614). The radial distance is based atleast in part on a round trip measurement associated with elapsed timebetween sending an outgoing signal from the base station 608 to themobile station 600 and receiving a corresponding acknowledgement signalfrom the mobile station 600 at the base station 608. The angularposition module 606 is in operative communication with the distancemodule 604 and calculates a current angular position of the mobilestation 600 in relation to the radial distance from the serving basestation 608. The current angular position is based at least in part on afirst signal strength measurement, a second signal strength measurement,and an angular position reference that extends outward from the servingbase station 608. The first and second signal strength measurementsrepresentative of power characteristics of respective RF signalsreceived by the mobile station 600 from corresponding first and secondsector antennas 610, 612 of the serving base station 608. The currentangular position may also be based on additional signal strengthmeasurements from other sector antennas 614 (e.g., sector antenna N).

In this embodiment, the apparatus may also include a location module 616in operative communication with the distance module 604 and angularposition module 606 for identifying a current geographic location of themobile station 600 in a coverage area of the wireless network 602 in ageographic notation based at least in part on combining the radialdistance and current angular position of the mobile station 600 relativeto the serving base station 608. In one embodiment, the radial distanceand current angular position reflect a polar coordinate-type ofgeographic notation in reference to the serving base station. In otherembodiments, the radial distance and current angular position can beconverted into various types of geographic notation, such as alatitude/longitude notation, an address notation, or a geo-bin tile gridnotation associated with the coverage area for the wireless network.

In the embodiment being described, the apparatus may also include anoutput module 618 in operative communication with the location module616 for sending the current geographic location of the mobile station600 in the geographic notation to a geo-location storage node 620associated with the wireless network 602. The geo-location storage node620 may be internal or external to the wireless network 602. In thisembodiment, the apparatus may include the serving base station 608. Inthis embodiment, the serving base station 608 may include the distancemodule 604, angular position module 606, location module 616, and outputmodule 618.

With reference to FIG. 7, an exemplary embodiment of an apparatus forestimating a geographic location of a mobile station 700 within acoverage area of a wireless network 702 includes a distance module 704and an angular position module 706. The distance module 704 determines aradial distance of the mobile station 700 from a base station 708serving the mobile station 700. The radial distance is based at least inpart on a round trip measurement associated with elapsed time betweensending an outgoing signal from the base station 708 to the mobilestation 700 and receiving a corresponding acknowledgement signal fromthe mobile station 700 at the base station 708. The angular positionmodule 706 is in operative communication with the distance module 704and calculates a current angular position of the mobile station 700 inrelation to the radial distance from the serving base station 708. Thecurrent angular position is based at least in part on a first signalstrength measurement, a second signal strength measurement, and anangular position reference that extends outward from the serving basestation 708. The first and second signal strength measurementsrepresentative of power characteristics of respective RF signalsreceived by the mobile station 700 from corresponding first and secondsector antennas 710, 712 of the serving base station 708. The currentangular position may also be based on additional signal strengthmeasurements from other sector antennas 714 (e.g., sector antenna N).

In this embodiment, the apparatus may also include a location module 716in operative communication with the distance module 704 and angularposition module 706 for identifying a current geographic location of themobile station 700 in a coverage area of the wireless network 702 in ageographic notation based at least in part on combining the radialdistance and current angular position of the mobile station 700 relativeto the serving base station 708.

In the embodiment being described, the apparatus may include ageo-location service node 722 associated with the wireless network 702and in operative communication with the serving base station 708. Inthis embodiment, the geo-location service node 722 may include thedistance module 704, angular position module 706, and location module716.

The geo-location service node 722 may also include an input module 724and an output module 718. The input module 724 in operativecommunication with the distance module 704 and angular position module706 for receiving the round trip measurement, first signal strengthmeasurement, and second signal strength measurement from the servingbase station 708 via the wireless network 702. The output module 718 inoperative communication with the location module 716 for sending thecurrent geographic location of the mobile station 700 in the geographicnotation to a geo-location storage device 726 associated with thegeo-location service node 722. The geo-location storage device 726 maybe internal or external to the geo-location service node 722. If thegeo-location storage device 726 is external to the geo-location servicenode 722, the geo-location storage device 726 may be internal orexternal to the wireless network 702.

With reference to FIG. 8, an exemplary embodiment of an apparatus forestimating a geographic location of a mobile station 800 within acoverage area of a wireless network 802 includes a distance module 804and an angular position module 806. The distance module 804 determines aradial distance of the mobile station 800 from a base station 808serving the mobile station 800. The radial distance is based at least inpart on a round trip measurement associated with elapsed time betweensending an outgoing signal from the base station 808 to the mobilestation 800 and receiving a corresponding acknowledgement signal fromthe mobile station 800 at the base station 808. The angular positionmodule 806 is in operative communication with the distance module 804and calculates a current angular position of the mobile station 800 inrelation to the radial distance from the serving base station 808. Thecurrent angular position is based at least in part on a first signalstrength measurement, a second signal strength measurement, and anangular position reference that extends outward from the serving basestation 808. The first and second signal strength measurementsrepresentative of power characteristics of respective RF signalsreceived by the mobile station 800 from corresponding first and secondsector antennas 810, 812 of the serving base station 808. The currentangular position may also be based on additional signal strengthmeasurements from other sector antennas 814 (e.g., sector antenna N).

In this embodiment, the apparatus may also include a location module 816in operative communication with the distance module 804 and angularposition module 806 for identifying a current geographic location of themobile station 800 in a coverage area of the wireless network 802 in ageographic notation based at least in part on combining the radialdistance and current angular position of the mobile station 800 relativeto the serving base station 808.

In the embodiment being described, the apparatus may include a networkmanagement node 828 associated with the wireless network 802 and inoperative communication with the serving base station 808. In thisembodiment, the network management node 828 may include the distancemodule 804, angular position module 806, and location module 816.

The network management node 828 may also include an input module 824, ameasurements storage device 830, and an output module 818. The inputmodule 824 for receiving the round trip measurement, first signalstrength measurement, and second signal strength measurement from theserving base station 808 via the wireless network 802. The measurementsstorage device 830 in operative communication with the input module 824,distance module 804, and angular position module 806 for storing theround trip measurement, first signal strength measurement, and secondsignal strength measurement. In this embodiment, the distance module 804retrieves the round trip measurement from the measurements storagedevice 830 in conjunction with determining the radial distance.Similarly, the angular position module 806 retrieves the first andsecond signal strength measurements from the measurements storage device830 in conjunction with calculating the current angular position. Theoutput module 818 in operative communication with the location module816 for sending the current geographic location of the mobile station800 in the geographic notation to the geo-location storage device 826.The geo-location storage device 826 may be internal or external to thenetwork management node 828. If the geo-location storage device 826 isexternal to the network management node 828, the geo-location storagedevice 826 may be internal or external to the wireless network 802.

With reference to FIG. 9, an exemplary embodiment of an angular positionmodule 906 associated with the apparatus of FIGS. 6-8 may include asource data communication sub-module 932 and a first angular componentsub-module 938. The source data communication sub-module 932 forretrieving first and second transmit parameter values from a storagedevice 936 associated with the wireless network. The first and secondtransmit parameter values representative of power characteristics ofrespective communication signals to be transmitted by the correspondingfirst and second sector antennas (e.g., 610, 612). In this embodiment,the first angular component sub-module 938 is in operative communicationwith the source data communication module 932 for determining adifference between the first and second transmit parameter values toobtain a first angular position component.

In a further embodiment of the angular position module 906, the sourcedata communication module may retrieve the first and second signalstrength measurements from the storage device 936. In this embodiment,the angular position module 906 may also include a second angularcomponent module 940 in operative communication with the source datacommunication module 932 for determining a difference between the firstand second signal strength measurements to obtain a second angularposition component.

In a yet further embodiment of the angular position module 906, thesource data communication sub-module 932 may also retrieve a firstantenna elevation gain parameter value, a first antenna maximum gainparameter value, and a first antenna azimuth gain parametercharacteristic from the storage device 936. The first antenna azimuthgain parameter characteristic relating first antenna azimuth gainparameter values to variable azimuth positions with respect to theangular position reference. The variable azimuth positionsrepresentative of prospective azimuth positions of the mobile station900 in relation to the angular position reference. The first antennaazimuth gain parameter characteristic based at least in part on a firstantenna position value representative of a first azimuth position atwhich the first sector antenna 910 is oriented in relation to theangular position reference.

In this embodiment, the source data communication sub-module 932 mayalso retrieve a second antenna elevation gain parameter value, a secondantenna maximum gain parameter value, and a second antenna azimuth gainparameter characteristic from the storage device 936. The second antennaazimuth gain parameter characteristic relating second antenna azimuthgain parameter values to the variable azimuth positions. The secondantenna azimuth gain parameter characteristic based at least in part ona second antenna position value representative of a second azimuthposition at which the second sector antenna 912 is oriented in relationto the angular position reference.

In the embodiment being described, the angular position module 906 mayalso include a third angular component sub-module 934 in operativecommunication with the source data communication sub-module 932. Thethird angular component sub-module 934 for selecting an angular value(e.g., not exceeding 360) for the variable azimuth position. The thirdangular component sub-module 934 using the first and second antennaazimuth gain parameter characteristics to identify the correspondingfirst and second antenna azimuth gain parameter values for the variableazimuth position associated with the selected angular value.

In this embodiment, the third angular component sub-module 934 may alsodetermine a difference between first and second transmit antenna gainsfor the selected angular value. The difference may be determined byadding the first antenna azimuth gain parameter value for the selectedangular value to the first antenna elevation gain parameter value andsubtracting the first antenna maximum gain parameter value to obtain thefirst transmit antenna gain, adding the second antenna azimuth gainparameter value for the selected angular value to the second antennaelevation gain parameter value and subtracting the second antennamaximum gain parameter value to obtain the second transmit antenna gain,and subtracting the second transmit antenna gain from the first transmitantenna gain to obtain a third angular position component.

The angular value selected for the initial variable azimuth position canbe based at least in part on knowledge of which sector antenna isserving the mobile station and the orientation and azimuth position ofthe serving sector antenna. Subsequent values selected for the variableazimuth position can be based on whether the subsequent result isapproaching or receding from the desired result. Various techniques canalso be used to select subsequent values for the variable azimuthposition based on the magnitude of the difference between the subsequentresult and the desired result as well as the change in the differencebetween consecutive subsequent results and the desired result.

For example, in a further embodiment of the angular position module 906,the angular value initially selected for the variable azimuth positionby the third angular component sub-module 934 may be between the firstand second antenna position values. In this embodiment, the initialangular value may be representative of a mid-point between the first andsecond antenna position values. In other words, if the first antenna isoriented to 120 degrees in relation to the angular reference position, asecond antenna may be oriented to 240 degrees, and 180 may be selectedas the initial angular value for the variable azimuth position becauseit is at a midpoint between the first and second sector antennas. Theselection of other angular values for the variable azimuth position cantake into account whether the results are getting better or worse toselect angular values to obtain better results. The iterative selectionof angular values can be incremental or based on a factor of thedifference between the obtained result and the desired result.

In a yet further embodiment, the angular position module 906 may includean arithmetic sub-module 942 and a control sub-module 944. In thisembodiment, the arithmetic sub-module 942 is in operative communicationwith the first, second, and third angular component modules 938, 940,934 for adding the first and third angular position components andsubtracting the second angular position component to form an arithmeticresult. In the embodiment being described, the arithmetic sub-module 942converts the arithmetic result to an absolute value. The controlsub-module 944 is in operative communication with the arithmeticsub-module 942 and the third angular component sub-module 934 foridentifying the angular value substituted for the variable azimuthposition as the current angular position for the mobile station 900 ifthe arithmetic result is within a predetermined threshold of a desiredvalue (e.g., zero). Otherwise, the control sub-module 944 may causes thethird angular component module 934 to repeat the selecting with adifferent angular value and the determining of the difference betweenthe first and second transmit gains to obtain a new value for the thirdangular position component, causes the arithmetic sub-module 942 torepeat the adding and subtracting to form the arithmetic result and thedetermining of the absolute value, and causes the repeating to continueuntil the arithmetic result is within the predetermined threshold of thedesired value.

In an alternate further embodiment, the arithmetic sub-module 942 may bein operative communication with the first, second, and third angularcomponent modules 938, 940, 934 for adding the first and third angularposition components and subtracting the second angular positioncomponent to form an arithmetic result. In the embodiment beingdescribed, the arithmetic sub-module 942 converts the arithmetic resultto an absolute value. In this embodiment, the control sub-module 944 maybe in operative communication with the arithmetic sub-module 942 and thethird angular component module 934 for causing the third angularcomponent sub-module 934 to repeat the selecting with a differentangular value and the determining of the difference between the firstand second transmit gains to obtain a new value for the third angularposition component, causing the arithmetic sub-module 942 to repeat theadding and subtracting to form the arithmetic result and the determiningof the absolute value, and causing the repeating to continue until theabsolute value is minimized. In the embodiment being described, thecontrol sub-module 944 identifies the corresponding angular valuesubstituted for the variable azimuth position for which the absolutevalue is minimized as the current angular position for the mobilestation 900.

In another alternate further embodiment, the arithmetic sub-module 942may be in operative communication with the first, second, and thirdangular component modules 938, 940, 934 for summing the first and thirdangular position components to form an arithmetic result. In theembodiment being described, the arithmetic sub-module 942 compares thearithmetic result to the second angular position component 940. In thisembodiment, the control sub-module 944 may be in operative communicationwith the arithmetic sub-module 942 and the third angular componentsub-module 934 for identifying the angular value substituted for thevariable azimuth position as the current angular position for the mobilestation if the arithmetic result is within a predetermined range of thesecond angular position component. Otherwise, the control sub-module 944causes the third angular component module 934 to repeat the selectingwith a different angular value and the determining of the differencebetween the first and second transmit gains to obtain a new value forthe third angular position component, causes the arithmetic sub-module942 to repeat the summing of the first and third angular positioncomponents to form the arithmetic result and the comparing of thearithmetic result to the second angular position component, and causethe repeating to continue until the arithmetic result is within thepredetermined range of the second angular position component.

With reference to FIG. 10, an exemplary embodiment of a non-transitorycomputer-readable medium storing program instructions that, whenexecuted by a computer, cause a corresponding computer-controlled deviceto perform a process 1000 for estimating a geographic location of amobile station within a coverage area of a wireless network. In oneembodiment, the process 1000 begins at 1002 where a radial distance of amobile station from a base station serving the mobile station isdetermined. The base station including multiple sector antennas. Theradial distance is based at least in part on a round trip measurementassociated with elapsed time between sending an outgoing signal from thebase station to the mobile station and receiving a correspondingacknowledgement signal from the mobile station at the base station. At1004, a current angular position of the mobile station in relation tothe radial distance from the serving base station is calculated. Thecurrent angular position is based at least in part on a first signalstrength measurement, a second signal strength measurement, and anangular position reference that extends outward from the serving basestation, the first and second signal strength measurementsrepresentative of power characteristics of respective RF signalsreceived by the mobile station from corresponding first and secondsector antennas of the serving base station. Next, a current geographiclocation of the mobile station in a coverage area of the wirelessnetwork may be identified in a geographic notation (1006).

In various embodiments, the program instructions stored in thenon-transitory computer-readable memory, when executed by the computer,may cause the computer-controlled device to perform various combinationsof functions associated with the various embodiments of the processes400, 500 for estimating a geographic location of a mobile stationdescribed above with reference to FIGS. 4 and 5. In other words, thevarious embodiments of the processes 400, 500 described above may alsobe implemented by corresponding embodiments of the process 1000associated with the program instructions stored in the non-transitorycomputer-readable memory.

Likewise, in various embodiments, the program instructions stored in thenon-transitory computer-readable memory, when executed by the computer,may cause the computer-controlled device to perform various combinationsof functions associated with the various embodiments of the apparatusfor estimating a geographic location of a mobile station described abovewith reference to FIGS. 6-8 and the angular position module 906described above with reference to FIG. 9.

For example, the computer-controlled device may include a base station(see FIG. 6, 608), a geo-location service node (see FIG. 7, 722), anetwork management node (see FIG. 8, 828), or any suitable communicationnode associated with the wireless network. Any suitable module orsub-module described above with reference to FIGS. 6-9 may include thecomputer and non-transitory computer-readable memory associated with theprogram instructions. Alternatively, the computer and non-transitorycomputer-readable memory associated with the program instructions may beindividual or combined components that are in operative communicationwith any suitable combination of the modules and sub-modules describedabove with reference to FIGS. 6-9

The above description merely provides a disclosure of particularembodiments of the invention and is not intended for the purposes oflimiting the same thereto. As such, the invention is not limited to onlythe above-described embodiments. Rather, it is recognized that oneskilled in the art could conceive alternative embodiments that fallwithin the scope of the invention.

1. A method for estimating a geographic location of a mobile stationwithin a coverage area of a wireless network, comprising: determining aradial distance of a mobile station from a base station serving themobile station, the base station including multiple sector antennas, theradial distance based at least in part on a round trip measurementassociated with elapsed time between sending an outgoing signal from thebase station to the mobile station and receiving a correspondingacknowledgement signal from the mobile station at the base station; andcalculating a current angular position of the mobile station in relationto the radial distance from the serving base station based at least inpart on a first signal strength measurement, a second signal strengthmeasurement, and an angular position reference that extends outward fromthe serving base station, the first and second signal strengthmeasurements representative of power characteristics of respective radiofrequency (RF) signals received by the mobile station from correspondingfirst and second sector antennas of the serving base station; whereinthe calculating of the current angular position of the mobile station isalso based at least in part on first and second transmit parametervalues representative of power characteristics of respectivecommunication signals to be transmitted by the corresponding first andsecond sector antennas.
 2. The method of claim 1, further comprising:identifying a current geographic location of the mobile station in acoverage area of the wireless network in a geographic notation based atleast in part on combining the radial distance and current angularposition of the mobile station relative to the serving base station. 3.The method of claim 2, further comprising: sending the currentgeographic location of the mobile station in the geographic notation toa geo-location storage node associated with the wireless network. 4.(canceled)
 5. The method of claim 2, further comprising: receiving theround trip measurement, first signal strength measurement, and secondsignal strength measurement from the serving base station via thewireless network at a geo-location service node associated with thewireless network; and sending the current geographic location of themobile station in the geographic notation to a geo-location storagedevice associated with the geo-location service node; wherein thereceiving, determining, calculating, identifying, and sending areperformed by the geo-location service node.
 6. The method of claim 2,further comprising: receiving the round trip measurement, first signalstrength measurement, and second signal strength measurement from theserving base station via the wireless network at a network managementnode associated with the wireless network; storing the round tripmeasurement, first signal strength measurement, and second signalstrength measurement at a measurements storage device associated withthe network management node; retrieving the round trip measurement,first signal strength measurement, and second signal strengthmeasurement from the measurements storage device in conjunction with thedetermining and calculating; and sending the current geographic locationof the mobile station in the geographic notation to a geo-locationstorage device associated with the network management node; wherein thereceiving, storing, retrieving, determining, calculating, identifying,and sending are performed by the network management node.
 7. The methodof claim 1, the further comprising: retrieving the first and secondtransmit parameter values from a storage device associated with thewireless network; and determining a difference between the first andsecond transmit parameter values to obtain a first angular positioncomponent of the current angular position of the mobile station.
 8. Themethod of claim 7, further comprising: determining a difference betweenthe first and second signal strength measurements to obtain a secondangular position component of the current angular position of the mobilestation.
 9. The method of claim 8, further comprising: retrieving afirst antenna elevation gain parameter value, a first antenna maximumgain parameter value, and a first antenna azimuth gain parametercharacteristic from the storage device, the first antenna azimuth gainparameter characteristic relating first antenna azimuth gain parametervalues to variable azimuth positions with respect to the angularposition reference, the variable azimuth positions representative ofprospective azimuth positions of the mobile station in relation to theangular position reference, the first antenna azimuth gain parametercharacteristic based at least in part on a first antenna position valuerepresentative of a first azimuth position at which the first sectorantenna is oriented in relation to the angular position reference;retrieving a second antenna elevation gain parameter value, a secondantenna maximum gain parameter value, and a second antenna azimuth gainparameter characteristic from the storage device, the second antennaazimuth gain parameter characteristic relating second antenna azimuthgain parameter values to the variable azimuth positions, the secondantenna azimuth gain parameter characteristic based at least in part ona second antenna position value representative of a second azimuthposition at which the second sector antenna is oriented in relation tothe angular position reference; selecting an angular value not exceeding360 for the variable azimuth position and using the first and secondantenna azimuth gain parameter characteristics to identify thecorresponding first and second antenna azimuth gain parameter values forthe variable azimuth position associated with the selected angularvalue; and determining a difference between first and second transmitantenna gains for the selected angular value by adding the first antennaazimuth gain parameter value for the selected angular value to the firstantenna elevation gain parameter value and subtracting the first antennamaximum gain parameter value to obtain the first transmit antenna gain,adding the second antenna azimuth gain parameter value for the selectedangular value to the second antenna elevation gain parameter value andsubtracting the second antenna maximum gain parameter value to obtainthe second transmit antenna gain, and subtracting the second transmitantenna gain from the first transmit antenna gain to obtain a thirdangular position component of the current angular position of the mobilestation.
 10. The method of claim 9, the calculating further comprising:adding the first and third angular position components and subtractingthe second angular position component to form an arithmetic result forwhich an absolute value is determined; and if the absolute value iswithin a predetermined threshold of a desired value, identifying theangular value substituted for the variable azimuth position as thecurrent angular position for the mobile station, otherwise, repeatingthe selecting with a different angular value, repeating the determiningof the difference between the first and second transmit gains to obtaina new value for the third angular position component, repeating theadding and subtracting to form the arithmetic result and the determiningof the absolute value, and continuing the repeating until the absolutevalue is within the predetermined threshold of the desired value. 11.The method of claim 9, the calculating further comprising: adding thefirst and third angular position components and subtracting the secondangular position component to form an arithmetic result for which anabsolute value is determined; repeating the selecting with a differentangular value, repeating the determining of the difference between thefirst and second transmit gains to obtain a new value for the thirdangular position component, repeating the adding and subtracting to formthe arithmetic result and the determining of the absolute value, andcontinuing the repeating until the absolute value is minimized; andidentifying the corresponding angular value substituted for the variableazimuth position for which the absolute value is minimized as thecurrent angular position for the mobile station.
 12. The method of claim9, further comprising: summing the first and third angular positioncomponents to form an arithmetic result and comparing the arithmeticresult to the second angular position component; and if the arithmeticresult is within a predetermined range of the second angular positioncomponent, identifying the angular value substituted for the variableazimuth position as the current angular position for the mobile station,otherwise, repeating the selecting with a different angular value,repeating the determining of the difference between the first and secondtransmit gains to obtain a new value for the third angular positioncomponent, repeating the summing of the first and third angular positioncomponents to form the arithmetic result and the comparing of thearithmetic result to the second angular position component, andcontinuing the repeating until the arithmetic result is within thepredetermined range of the second angular position component.
 13. Anapparatus for estimating a geographic location of a mobile stationwithin a coverage area of a wireless network, comprising: a distancemodule for determining a radial distance of a mobile station from a basestation serving the mobile station, the base station including multiplesector antennas, the radial distance based at least in part on a roundtrip measurement associated with elapsed time between sending anoutgoing signal from the base station to the mobile station andreceiving a corresponding acknowledgement signal from the mobile stationat the base station; and an angular position module in operativecommunication with the distance module for calculating a current angularposition of the mobile station in relation to the radial distance fromthe serving base station based at least in part on a first signalstrength measurement, a second signal strength measurement, and anangular position reference that extends outward from the serving basestation, the first and second signal strength measurementsrepresentative of power characteristics of respective radio frequency(RF) signals received by the mobile station from corresponding first andsecond sector antennas of the serving base station; wherein thecalculating of the current angular position of the mobile station isalso based at least in part on first and second transmit parametervalues representative of power characteristics of respectivecommunication signals to be transmitted by the corresponding first andsecond sector antennas.
 14. The apparatus of claim 13, furthercomprising: a location module in operative communication with thedistance module and angular position module for identifying a currentgeographic location of the mobile station in a coverage area of thewireless network in a geographic notation based at least in part oncombining the radial distance and current angular position of the mobilestation relative to the serving base station.
 15. The apparatus of claim14, further comprising: an output module in operative communication withthe location module for sending the current geographic location of themobile station in the geographic notation to a geo-location storage nodeassociated with the wireless network.
 16. The apparatus of claim 15, theapparatus comprising: the serving base station, the serving base stationincluding the distance module, angular position module, location module,and output module.
 17. The apparatus of claim 14, the apparatuscomprising: a geo-location service node associated with the wirelessnetwork and in operative communication with the serving base station,the geo-location service node including: the distance module, angularposition module, and location module; an input module in operativecommunication with the distance module and angular position module forreceiving the round trip measurement, first signal strength measurement,and second signal strength measurement from the serving base station viathe wireless network; and an output module in operative communicationwith the location module for sending the current geographic location ofthe mobile station in the geographic notation to a geo-location storagedevice associated with the geo-location service node.
 18. The apparatusof claim 14, the apparatus comprising: a network management nodeassociated with the wireless network and in operative communication withthe serving base station, the network management node including: thedistance module, angular position module, and location module; an inputmodule for receiving the round trip measurement, first signal strengthmeasurement, and second signal strength measurement from the servingbase station via the wireless network; a measurements storage device inoperative communication with the input module, distance module, andangular position module for storing the round trip measurement, firstsignal strength measurement, and second signal strength measurement,wherein the distance module retrieves the round trip measurement fromthe measurements storage device in conjunction with determining theradial distance and the angular position module retrieves the first andsecond signal strength measurements from the measurements storage devicein conjunction with calculating the current angular position; and anoutput module in operative communication with the location module forsending the current geographic location of the mobile station in thegeographic notation to a geo-location storage device associated with thenetwork management node.
 19. The apparatus of claim 13, the angularposition module comprising: a source data communication sub-module forretrieving the first and second transmit parameter values from a storagedevice associated with the wireless network; and a first angularcomponent sub-module in operative communication with the source datacommunication sub-module for determining a difference between the firstand second transmit parameter values to obtain a first angular positioncomponent of the current angular position of the mobile station.
 20. Theapparatus of claim 19, the angular position module further comprising: asecond angular component sub-module in operative communication with thesource data communication sub-module for determining a differencebetween the first and second signal strength measurements to obtain asecond angular position component of the current angular position of themobile station.
 21. The apparatus of claim 20 wherein the source datacommunication sub-module is also for: retrieving a first antennaelevation gain parameter value, a first antenna maximum gain parametervalue, and a first antenna azimuth gain parameter characteristic fromthe storage device, the first antenna azimuth gain parametercharacteristic relating first antenna azimuth gain parameter values tovariable azimuth positions with respect to the angular positionreference, the variable azimuth positions representative of prospectiveazimuth positions of the mobile station in relation to the angularposition reference, the first antenna azimuth gain parametercharacteristic based at least in part on a first antenna position valuerepresentative of a first azimuth position at which the first sectorantenna is oriented in relation to the angular position reference; andretrieving a second antenna elevation gain parameter value, a secondantenna maximum gain parameter value, and a second antenna azimuth gainparameter characteristic from the storage device, the second antennaazimuth gain parameter characteristic relating second antenna azimuthgain parameter values to the variable azimuth positions, the secondantenna azimuth gain parameter characteristic based at least in part ona second antenna position value representative of a second azimuthposition at which the second sector antenna is oriented in relation tothe angular position reference; and the angular position module furthercomprising: a third angular component sub-module in operativecommunication with the source data communication sub-module for:selecting an angular value not exceeding 360 for the variable azimuthposition and using the first and second antenna azimuth gain parametercharacteristics to identify the corresponding first and second antennaazimuth gain parameter values for the variable azimuth positionassociated with the selected angular value; and determining a differencebetween first and second transmit antenna gains for the selected angularvalue by adding the first antenna azimuth gain parameter value for theselected angular value to the first antenna elevation gain parametervalue and subtracting the first antenna maximum gain parameter value toobtain the first transmit antenna gain, adding the second antennaazimuth gain parameter value for the selected angular value to thesecond antenna elevation gain parameter value and subtracting the secondantenna maximum gain parameter value to obtain the second transmitantenna gain, and subtracting the second transmit antenna gain from thefirst transmit antenna gain to obtain a third angular position componentof the current angular position of the mobile station.
 22. The apparatusof claim 21, the angular position module further comprising: anarithmetic sub-module in operative communication with the first, second,and third angular component sub-modules for adding the first and thirdangular position components and subtracting the second angular positioncomponent to form an arithmetic result for which an absolute value isdetermined; and a control sub-module in operative communication with thearithmetic sub-module and the third angular component sub-module foridentifying the angular value substituted for the variable azimuthposition as the current angular position for the mobile station if theabsolute value is within a predetermined threshold of a desired value,otherwise, the control sub-module causes the third angular componentsub-module to repeat the selecting with a different angular value andthe determining of the difference between the first and second transmitgains to obtain a new value for the third angular position component,causes the arithmetic sub-module to repeat the adding and subtracting toform the arithmetic result and the determining of the absolute value,and causes the repeating to continue until the absolute value is withinthe predetermined threshold of the desired value.
 23. The apparatus ofclaim 21, the angular position module further comprising: an arithmeticsub-module in operative communication with the first, second, and thirdangular component sub-modules for adding the first and third angularposition components and subtracting the second angular positioncomponent to form an arithmetic result for which an absolute value isdetermined; a control sub-module in operative communication with thearithmetic sub-module and the third angular component sub-module forcausing the third angular component sub-module to repeat the selectingwith a different angular value and the determining of the differencebetween the first and second transmit gains to obtain a new value forthe third angular position component, for causing the arithmeticsub-module to repeat the adding and subtracting to form the arithmeticresult and the determining of the absolute value, and for causing therepeating to continue until the absolute value is minimized, wherein thecontrol sub-module identifies the corresponding angular valuesubstituted for the variable azimuth position for which the absolutevalue is minimized as the current angular position for the mobilestation.
 24. The apparatus of claim 21, the angular position modulefurther comprising: an arithmetic sub-module in operative communicationwith the first and third angular component modules for summing the firstand third angular position components to form an arithmetic result andfor comparing the arithmetic result to the second angular positioncomponent; and a control sub-module in operative communication with thearithmetic sub-module and the second and third angular componentsub-modules for identifying the angular value substituted for thevariable azimuth position as the current angular position for the mobilestation if the arithmetic result is within a predetermined range of thesecond angular position component, otherwise, the control sub-modulecauses the third angular component sub-module to repeat the selectingwith a different angular value and the determining of the differencebetween the first and second transmit gains to obtain a new value forthe third angular position component, causes the arithmetic sub-moduleto repeat the summing of the first and third angular position componentsto form the arithmetic result and the comparing of the arithmetic resultto the second angular position component, and causes the repeating tocontinue until the arithmetic result is within the predetermined rangeof the second angular position component.
 25. A non-transitorycomputer-readable medium storing program instructions that, whenexecuted by a computer, cause a corresponding computer-controlled deviceto perform a method for estimating a geographic location of a mobilestation within a coverage area of a wireless network, the methodcomprising: determining a radial distance of a mobile station from abase station serving the mobile station, the base station includingmultiple sector antennas, the radial distance based at least in part ona round trip measurement associated with elapsed time between sending anoutgoing signal from the base station to the mobile station andreceiving a corresponding acknowledgement signal from the mobile stationat the base station; calculating a current angular position of themobile station in relation to the radial distance from the serving basestation based at least in part on a first signal strength measurement, asecond signal strength measurement, and an angular position referencethat extends outward from the serving base station, the first and secondsignal strength measurements representative of power characteristics ofrespective radio frequency (RF) signals received by the mobile stationfrom corresponding first and second sector antennas of the serving basestation, wherein the calculating of the current angular position of themobile station is also based at least in part on first and secondtransmit parameter values representative of power characteristics ofrespective communication signals to be transmitted by the correspondingfirst and second sector antennas; and identifying a current geographiclocation of the mobile station in a coverage area of the wirelessnetwork in a geographic notation based at least in part on combining theradial distance and current angular position of the mobile stationrelative to the serving base station.
 26. The non-transitorycomputer-readable medium of claim 25, the method further comprising:retrieving the first and second transmit parameter values from a storagedevice associated with the wireless network; and determining adifference between the first and second transmit parameter values toobtain a first angular position component of the current angularposition of the mobile station.